US President Barack Obama today, proposed to close tax loopholes for the wealthiest Americans as part of the new economic strategy he plans to unveil in this year's State of the Union address.

However, the plan, which includes raising the top tax rate on capital gains, charging financial firms a fee for heavy borrowing, and changing the tax rules for trust funds, is unlikely to pass in its current form in Congress, where, as of this month, Republicans control both houses.

In a fact sheet, the White House argued the US "tax code is unfair, allowing the rich to play by different rules.

"Contending that "the 400 richest taxpayers paid an average tax rate below 17 per cent in 2012, lower than many middle class families," the White House said Obama's proposals aim to "help level the playing field for the middle class."